What to look for buying 2 hand laptop

Hello my nehbor is trna sell me a laptop for 1k and he said it was like 2.3k im thinkng about doing it cuz he needs the money and i alr thinking about spend 1.2k for a pc amd i wint have money for the monitor keyboard and all That but what should i be looking for to make sure it runs good( i forgot what laptop it was but i say a eye in it so im oretty sure its a asus) i dont know anything about pc/laptops so what should inlook for to make Sure it works fine and im not getting scammed if it helps i could ask him what laptop it is